1. Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
2. Deutsche Gesellschaft für Internationale Zusammenarbeit, Asokoro, Abuja 900103, Nigeria
3. Warwick Centre for Global Health, Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
4. Division of Epidemiology and Biostatistics, Department of Global Health, Stellenbosch University, Stellenbosch 7602, South Africa
5. Department of Public Health (IHCAR), Karolinska Institutet, 171 77 Stockholm, Sweden